Exploding star observations challenge current understanding of universe's expansion speed.

Two new papers led by Patrick Kelly at the University of Minnesota have used a new technique involving light from an exploding star that arrived at Earth via multiple winding routes through the expanding universe to measure the Hubble constant, which determines how fast the universe is expanding. While the results do not quite resolve the tension around the Hubble constant, they do give us another clue and more questions to ask. The new method involves gravitational lensing, and the papers find that the measurement is closer to the cosmic microwave background measurement, rather than the nearby Cepheid and supernova measurement.